(Bloomberg) -- Spain’s populist Podemos party said it would join an alliance of left-wing groups in a last-ditch attempt to help Socialist Prime Minister Pedro Sanchez prevent a right-wing coalition from taking power in next month’s snap election.

The Spanish electoral system rewards larger coalitions and a leftist alliance including Podemos would give Sanchez a chance of holding onto power. It could also make the left-wing alliance’s leader — Deputy Prime Minister Yolanda Diaz who is the country’s most popular politician — into a king maker.

Sanchez called the surprise July 23 vote last month after the conservative People’s Party crushed his Socialists in regional and municipal elections. Support from a united alliance between Podemos and Diaz’s Sumar group could enable him to block right-wing parties from getting the majority of 176 seats in parliament needed to form a government.

“I say it clearly, we will run together with Sumar in the general elections,” Ione Belarra, Podemos secretary general, told reporters on Friday, adding that her party’s support was contingent on Sanchez fielding ministers it could back. 

King Maker

The move thrusts Diaz, a member of the communist party, into the limelight as she’ll likely play a pivotal role in who will be the next prime minister.

While the PP, led by Alberto Nunez Feijoo, is widely projected to win the election, it will probably need the support of the far-right Vox party to form a government, most polls suggest.

Feijoo has said he would prefer to govern alone, but hasn’t publicly ruled out a coalition with Vox. The party founded by former PP members has pledged to outlaw Catalan and Basque nationalist parties and build a wall around the North African exclaves of Ceuta and Melilla to halt the flow of immigrants.

Despite the unification of the far-left parties, Sanchez still faces an uphill battle. According to a new opinion poll, the PP would still win even with the stronger coalition on the left. 

Culture Wars

Both Sanchez and Diaz have highlighted conservative ties with Vox and Diaz has tried to rally the far left against the prospect of such a government, which she claims will reverse progressive laws that promote gender equality and minority rights.

Feijoo this week pledged that if he wins the election he’ll abolish a groundbreaking self-determination law that makes it easier for people over the age of 16 to legally change their gender. Vox has appealed against the law in the country’s top court, arguing it will allow men to use women’s bathrooms and make competitive sports unfair.

The daughter of a union leader from the northern region of Galicia and a lawyer with little political experience, Diaz was named labor minister in 2020 in Sanchez’s coalition government.

During the Covid pandemic, the soft-spoken 52-year-old gained popularity for overseeing a furlough program that preserved thousands of jobs in peril during lockdown. She built a reputation as a consensus builder after reaching a series of agreements with unions and employer groups to raise the minimum wage, regulate gig economy workers and push for a sweeping labor reform.

Her labor-market overhaul has been celebrated by the government for reducing chronically high unemployment and temporary contracts, but the opposition says the law merely distorts statistics by creating a figure called “discontinued fixed-employees” that artificially raises the number of fixed jobs for seasonal workers. Her reform is seen as a model to follow by the government of Brazilian President Luiz Inacio Lula da Silva.

Diaz has clashed with other party leaders over control of the progressive movement, which has maintained a tense alliance with Sanchez’s party.

After challenging the socialists’ hegemony of the left as recently as 2015, Podemos’ national appeal has waned after pushing for controversial legislation to cap housing rentals and a sexual consent law that had the unintended side-effect of reducing the jail time of hundreds of convicted sex offenders.

(Updates with Podemos comment in the fourth paragraph.)

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